SLN Pre-Amp - Elektor Aug 1982

[Kay]

Thanks,

if you need my layout/schematic as pdf,
I will post it

[scafas]

I built this preamp according to the letter to the wiring diagram, it works perfectly but the sound 'pissed brilliant high frequencies and poor at low frequencies.
how can I tweak the circuit to obtain a balanced sound?

[tiefbassuebertr]

Originally Posted by GlidingDutchman

I want to attempt building this phono pre-amp (see attached schem).

Any tips and ideas on how to possibly improve the circuit?

I am going to configue it for MC cartridges.

Yes. I would say, the choice of input transistors in parallel mode isn't the best, because only 0,22mA/each transistor is adjust (15V/68K).
Unfortunately I am not able, to call you the ideal choice. Maybe jFETs are a better choice.

[Kay Pirinha]

Originally Posted by scafas

I built this preamp according to the letter to the wiring diagram, it works perfectly but the sound 'pissed brilliant high frequencies and poor at low frequencies.
how can I tweak the circuit to obtain a balanced sound?

Does the total capacitance value in parallel to the inputs match to the value given in your cartridge's data sheet?

Best regards!

[scafas]

i don't know .
i have a MISSION SOLITAIRE and i put a 100pf cap on input pre.
it's correct?

[Kay Pirinha]

I also don't know. Just have a look on it's datasheet.

Best regards!

[tiefbassuebertr]

Originally Posted by tiefbassuebertr

Yes. I would say, the choice of input transistors in parallel mode isn't the best, because only 0,22mA/each transistor is adjust (15V/68K).
Unfortunately I am not able, to call you the ideal choice. Maybe jFETs are a better choice.

german version from Elektor is read about
http://www.magnetofon.de/supra/Supra_Elektor.pdf
basic description of the topology you will find there:
The most linear stage for large voltage swings - Lender's Circuit
main disadvantage I mentioned in my last post.
I want to modify the circuit in such way, that each input transistor runs with 3mA instead only 0,22 mA idle current. Secondly I want to use for the outputs power darlingtons (like BD675/BD676) an idle current between 50-100 mA.
How I calculate the new values of the resistors R11/13/14 (pos. half) so as R10/18/19 (neg. half) from the first pdf link here ?
Thank you very much for advices.
Best thanks in advance.